Portable electric automobile hoist



2 Sheets-Sheet 1 E. B. THOMPSON PORTABLE ELECTRIC AUTOMOBILE HOIST Filed May 4, 1936 Oct 27, 1936.

E. B. THOMPSON PORTABLE ELECTRIC AUTOMOBILE HOIST Filed May 4, 1956 2 Sheets-Sheet 2 jaw/2; [Ina/A? [flaw 05022 @w iw Patented on. 27, 1936 UNITED "STATES,

PATENT OFFICE PORTABLE ELECTRIC AUTOMOBILE HOIS'I.v

Elmer B. Thompson, Des Moines, Iowa, 'assignor to Globe Machinery & Supp y Company, Dc Molnes, Iowa, a corporation of Iowa Application May "4, 1936, Serial No. dust 120mm. (01.254-89) are above the floor or surface upon which the.

machine rests, and characterized by having four upright posts at the corners formed with gear teeth and a frame movable up and down on the posts'and having an electric motor operatively. connected to the gear wheel meshing with each of the racks, andwhereby when. the motor is run in one direction the gears will raise the frame 1 and when the motor is run in the opposite direc tion the gears will lower the frame, and also characterized by having a switch lever for the electric motor, which'switch lever when in normal position cuts off the current of the motor and when in one of its operative positions causes the motor to turn in a direction for raising the lift and when in its other operative. position causes the motor to rest in a direction for lowering the lift, and further characterized by having safety pawls carried by the frame for each of the racks to prevent'lowering of the frame in the event that the electric current to the motor should fail or for any other reason.

The object of mypresent invention is to pro vide a combined switch" lever locking and pawl withdrawing device of simple, durable and inexpensive construction, and so constructed and arranged that when the switch lever is in either of its operative positions it cannot be moved to the other operative position without first manually withdrawing the locking lever, and thereby avoiding the possibility of reversing themotor during either the up or down movement of the lift.

A'further object is to provide means whereby when the said locking lever is moved to its with drawn position it will automatically move the pawls to their withdrawn position so that the lift may move downwardly. and at the same time automatically apply a brake to the driving mechanism for the gear wheels to avoid the possibility of the motor coasting by reason of the momentum of the pulley.

A further object is to provide a device of this class in which, and in the event that during a lowering movement of the frame the movement should be stopped by reason of some object in the path of the frame, then the continued rotation of the gear wheels will cause some of the posts to continue to be moved upwardly by the gears until the motor is automatically stopped, I

thereby avoiding the possibility of causing injury to the left on account of such interrupted down ward movement before the. automatic stopping of the motor.

In the accompanying drawings Figure 1. shows a top or plan view of a lift embodying my inven- 5 tion, a portion of the frame being broken away to show the arrangement of the gear wheel operating mechanism.

Figure 2 shows a side. elevation of one of the posts and gear wheel for engaging the rack on,the 119.

post.

Figure 3 shows a front elevation of one of the posts provided with a rack, and a portion of the movable frame and motor.

Figure 4 shows an enlarged detail side elevation 15? of one of the posts and illustrating on the posts one of the gear wheels and one of the pawls, and

illustrating my improved combined switch lever locking and pawl withdrawing devices, with the switch lever in positio'nfor causing the frame to 205 be elevated.

Figure 5 shows asimilar view with the locking lever in its withdrawn position.

Figure 6 shows a similar view with theswitch lever in neutral position and illustrating the posi- 5; tion of the. locking leverto prevent movement of the switch lever to position for lowering the lift.

Figure 7 shows a detail perspective view illustrating the switch lever and the locking lever for the pawl, showing the locking lever in position for 3 p. preventing downward movement of the switch lever. Figure 8 shows a vertical sectional view thron one of the cross members of the frame and illustrating the means for connecting the various g5 pawls whereby they may be operated in unison; and

Figure 9 shows a perspective view illustrating my improved lift with an object under one end of the lift to prevent that end from lowering, 4c and illustrating the upward movement of the adjacent posts when the gear mechanism continues to operate after the downward movement of the lift has been prevented by such object.

. Referring to the accompanying drawings, my

device comprises a frame consisting of two cross pieces l0, two longitudinal members ii, and a frame member at one corner, indicated generally by the reference numeral l2. Mounted upon this frame member i2 is a platform l3 for supporting an electric motor l4. At the opposite corners of the mainframe there are frame members I 5, and in each of the frame members I2 and I5 there is provided an upright post indicated generally by. the numeral l6, and formed .at one side with rack 65.-

of the posts to the lower end, and when the gear wheel l8, shown in Figure 2, moves upwardly 6 beyond the rack it will enters notch 19 and when in said notch 'may continue to rotate without affecting the post. Each of the posts is provided at its lower end with an opening extending upwardly, and a suppo ting platen, shown in Figure 3, is provided with a pin 2| which normally extends up into this opening and. prevents lateral movement of -the lower end of the post. These frame'members l2 and I 5 form-guides for holding the posts in upright positions, and permit the frames to move up and down relative to the posts".

The electric motor. i4 is connected by belts 22,

.with a pulley 23, which latter is operatively con- 5 nected by means not herein shown, with the gear wheel l8, and this gear wheel I8 is connected by shafts 24' and beveled pinions 25, the corresponding gear wheel l8 engaging each of theracks on the four posts, and more fully illustrated and described in my said "co-pending application.

Mounted in the frame I2 is a shaft 26, and fixed 25 to this shaft is a pawl 21. At one end of this shaft 25 is an arm 28 to which a rod 29 is-fixed. This rod. 29 connects to an arm 30 on the shaft3l, and

another arm 32 is fixed to the shaft 3| and is connected to a rod 33; which extends to a similar 30 arm 34 on another one ofthe posts, and by this means it is connected to the shaft 35, and this shaft has an arm 36 connected by a link 31 with an arm 38 on the shaft 39, towhich another one of the pawls 21 is fixed. By this means all of the pawls are operatively connected in such manner that when the pawl 21 is moved, outwardly the other pawls will move outwardly, and when the pawl 21 is moved inwardly toward the rack the other pawls will be correspondingly moved. Each- 40 pawl, however, is provided with a spring 40 wherej by when it is in its operative position it may move over the teeth of the rack and enter the spaces between the racks to thereby permit raising movement of the frame and prevent lowering move-- ment.

The operation of the mechanism just described is substantially the same as that ofthe mechanism described in my said copending application, and provides a structure by which, when the electric motor is operated inone direction, the pawls will all be in engagement with the racksand the drivns ears will be rotated in a direction for elevating theframe. when the motor is stopped, the

frame-is stationary, and when the motor is moved 56 in the other direction the pawls will be withdrawn and the gear wheels will be rotated in a direction for moving the frame downwardly.

For controlling the movements of the motor I have provided a switch box, indicated generally by the reference numeral 4|, from which projects the switch shaft 42 shown in Figure 3. The switch is of, ordinary construction, and partial rotation of the shaft 42 operates the switch to reverse the rotation of the motor or cut off the current to hold the motor stationary. This switch is of ordinary construction and is not herein shown or described in detail.

Fixed to the switch'shaft 42 is a .switch controllinglever 43 which is connected by a link 44 70.with 'a manually operable switch lever 45 fulcrumed on the shaft 25. On this switch'lever'45 is an arm 45 projecting laterally for purposes hereinafter made clear. For automatically operating the switch controlling lever 43 I have pro-- vided an upright bar 41 supported-on the adjacent ually operated lever 45, except as limited by the w 2,039,059 7 teeth n. As will be seen in Figure 2, thisrack 11' post and having at its upper end an outwardly extended pin 48 and at its lower end an outwardly extending pin 49. These pins are arranged in the path of the switch controlling lever 43. When the switch controlling lever "is in the position 5 shown in Figure 5, then the electric motor is operated in a direction to lower the frame, and when the lever 43 strikes the lower pin 49 it moves the lever 43 to a substantially horizontal position, as shown in Figure 6,.which causes the switch to cut off the current to the motor, and when the switch controlling lever 43- is in the inclined position shown in Figure 4, then the switch is inposition for causing the motor to rotate in a direction for raising the frame, and when the lever 43 engages the upper pin 48 the lever 43 is again thrown to its substantially horizontal or neutral position. The movement of the lever 43, however, can be controlled by the man- 20 locking mechanism hereinafter described.

The switch locking mechanism comprises a combined locking lever and pawl withdrawing lever pivoted to the frame l2 and indicated by the numeral 50. This lever is provided at one side with a laterally extendingv shoulder 5| and is connected to the adjacent pawl 21 by a link 52 having a slot 53 therein through which a pin 54 is extended, and this pin is connected to the lever "50. A spring 55 is connected to the lever 50 and to the adjacent portion of the frame l2 so that the.lever,50 is thereby yieldingly held in its normal position.- The function of this locking lever is to prevent a movement of the switch lever 45 from either of its operative positions to the other, 35 so that, for instance, when the frame is moving upwardly the current cannot be instantly reversed to start it to move downwardly, which movement would be prevented by 'the pawls engaging the. racks, and would result in injury to some of the 40 mechanism. Furthermore, the function of this locking member 50 is to prevent the possibility of reversing the motor when the lift is moving downwardly, because that would exert undue strains upon the motor and other mechanism. A further object of this locking lever is to provide means whereby during any movement of the electric motor in a direction forlowering the lift, the pawls will all be held in their withdrawn positions to permit suchdownward movement. These desirable'results were attained in my improved device by the construction and arrangement of the locking lever 50 relative to the switch lever 45. To illustrate:

In Figure 4 the switch lever 45 is in an elevated position, and when in this'positlon the switch is operated to rotate the electric motor in a dimotion for raising the frame. When in this position, andif the switch lever is moved downwardly, the arm 45 on the switch lever 45 will engage the shoulder 5i on the locking lever 55 and prevent movement of the switch lever 45 beyond its neutral position, andall that an operator may do by manipulating the switch lever is to stop the rotation of the motor, and if after that is done it is desired to lower the lift, then the operator must manually move the locking lever 53 outwardly far enough to permit the arm 45 on the switch lever 45 to pass the shoulder 5| on the locking lever, and when this is done the link 52 moves thepawl outwardly'away from the rack, as shown inFigure 5, so that when the lift is moved downwardly the pawls will all be in their withdrawn position. When the frame is' moving downwardly, thenthe parts are in the position shown in Figure 5, and 75 it must be raised, but can only be raised until the arm 46 strikes the under side of the projecting end of the shoulder and then before the switch levor45 can be moved upwardly to cause the frame to be raised,- the operator must manually move the lever 50 outwardly to permit such movement,

and when the lever 56 is released after such movement its spring 55 will return it to normal posi-' tion and permit the pawls 21 to again engage their respective racks. So long, however, as the switch lever 45 is in position for causing the motor to rotate the gears in an operation for moving the frame downwardly it is necessary that the pawls 21 be held in their withdrawn positions, and this is accomplished by the arm 46 on the lever 45 being in the position shown'in Figure 5, that is to say, across the front edge-of the locking lever .50,

thereby securely holding this locking lever against inward movement toward the rack, and in position for holding the pawl out of engagement with the rack; and before the switchlever 45 can be moved to position for raising the lift, the locking lever 45 must be further withdrawn to permit the .arm 46 to pass above the projecting part of the shoulder 5|.

. In practical operation with this safety device for the electric switch it will be seen that the said locking lever as associated with the switch lever forms a highly eflicient safety device. In practice it is frequently desirable to stop the frame. at various points throughout its upward movement and before it reaches its upper limit, and it is frequently necessary to cause the frame to move up and down just a few inches to permit an operator to have access to the desired part of an' automobile'on the frame. pbviously, if the gear wheels turn in the direction for iowering'thecause of the arm 46 being in the path of the locking lever; Y r

In my improved automatic brake device for preventing the motor from coasting during a downward movement of the frame I have provided the following mechanism: Mounted on the frame [2' beneath the motor is ashaft 56 having on one end an arm 51, to which a brake shoe 58 is pivoted. This brake shoe is positioned to engage the surface of the pulley 23. On the opposite end of the shaft 56 is an arm 59, connected by a spring 60- with an arm 6i fixed to the shaft 26, which shaft and when the locking lever is moved to its withalsohas the pawlsZ'l fixed to it. By this means,

drawn position'tdreleasethe pawls, then the 'brake is applied to the pulley 23 with enough yielding friction to-prevent the motor from coasting and the frame can move downwardly only by a'rotation of the motor. Byconnecting this brake for operation with the safety lever only I-have provided means whereby'the action of the brake is entirely automatic and is applied only when the pawls are out of. engagement with the rack nd the frame is being moved downwardly.

In practice wlth'my improved lift, and under conditions with a heavy automobile mounted on the frame, I havefrequently requested inexperienced operators to raise and lower the lift and 2,059,059 7 in order to bring the lever l5 to neutral position,

have explained only that the lever was the 7 electric switch controlling lever and the lever 56 was the safety locking lever, and I have found that such inexperienced persons can at once fully control all of the operations of the lift, stopping it at any point of its elevation and causing it to move either upwardly or downwardly from this stoppingpoint without danger of injury to the hoist. Under all circumstances the safety pawls are always in position when the lift is moving upwardly and the safety pawls are always in withdrawn positions when the lift is moving downwardly. Furthermore, the switch lever 45 cannot be moved from either of its operative positions to the other without first shutting off the current of the motor and then manually ,operatingthe lever 50, to permit such reverse movement of the motor, and, also, under all conditions the brake is automatically applied when thewheel, switch mechanism associated with the motor, a spring actuated .pawl carried by the frame and normally engaging the rack to prevent downward movement of the frame, a switch lever fulcrumed to the frame and operatively connected with said switch mechanism, a locking lever fulcrumed to the frame and normally in such position that it will prevent movement of the said switch lever to position for causing the motor to lower the frame but will permit such movement of the switch lever when the locking lever is moved to a withdrawnposition, and means operated by a movement of the locking lever to said'withdrawn position for moving said pawl ,away from said rack.

2. In a hoist of'the class described, the combination of an upright post, a rack on the post, a frame capable of up nd down movement on the post, an electric mo r carried by the frame, a gear. wheel carried by the frame, means for operativelys'connecting the motor with the gear wheel, switch mechanism associated with the motor, aspringactuated pawl carried by'the frame and normally engaging the rack to prevent downwardmovementof the frame, a switch lever fulcrumed to the frame and operatively connected with said switch mechanism, a locking lever fulcrum'ed to the frame and normallyin such position that it will prevent movement of the said 'switch lever to position for causing'the motor to lower the frame but will permit such movement of the-switch lever when the locking lever is'moved to a withdrawn position, means operated by a movement of the locking lever to said withdrawn position for moving said pawl away from said rack, and a spring for normally hold-.

ing said locking lever in said normal position.

3. In a hoist of the class described, the.com-

binatiohof an upright post, a rack on the post,

a frame capable of up and down'movem'ent on the post, an electric motor carried by the frame,

a gear wheel carried by the frame, means for' operativeiy connecting the motor withthe gear wheel, switch mechanism associated with the motor, a spring actuated pawl carried bysthe frame.

, lower the frame but will permit such movement crumed to the frame and operatively connected with said switch mechanism, a locking leverfulcrumed to the frame and normally in such position that it will prevent movement of the said switch leverto position for causing the motor to of the switch lever when the locking lever is moved to a withdrawn position, means operated by a movement of the locking lever to said withdrawn position for moving said pawl away from said rack, a brake for the motor and its driv-' ing connections to the gear wheel, and meansoperated bya movement of the pawl away from the rack for applying the brake prevent the mo- V tor from coasting. I

4. In a hoist of the class described; the combination of an upright post, a rack on the post,

a frame capable of up and down movement on the post, an electric motor'carried by the frame, a gear'wh'eel carried by the frame, means for operatively connecting the motor with the gear wheel, switch mechanism associated with the ,Vmotor, a spring actuated pawl carried by the.

frame and normally engaging therack to prevent downward movement of the frame, a switch lever I fulcrumed to the frame and operatively connected with said switch mechanism, a locking lever fulcrumed to the frame and normally in such position that it will prevent movement of the said switch leve'r'to position for causing the motor to lower the frame but will permit such movement of the switch lever when the locking lever is movedto a withdrawn-position, said switch lever and saidlocking lever being pro-- vided with means whereby when the switch lever is in position for causing the frame to move its withdrawn position.

downwardly said switch leve'r cannot be moved .to position for causing the frame to move upwardly without first moving the locking lever to a frame capable of up and down movement on I 5. In a hoist of the class described, the combination'of an upright post, a rack on-the post,

a frame capable of up and down movement on I the post, an electric motor-carried'by the frame, a gear wheel carried by the frame, means for operatively connecting the motor "with the gear wheel, switch mechanism associated with the motor, a' spring actuated pawl carried by the frame and normally engaging 'theracl: to prevent downward movenient of Lthe frame, a switch lever fulcrumed= to the frame and operatively connected with said switch mechanism, a locking lever fulcrumed to the frame and normally in such position that it will prevent movement r of the said switch lever to position for causing the motor to lowerthe frame but. will permit -such movement of the switch lever when the Y said switch lever and said locking lever being' locking lever is moved to a withdrawn position,

providedwith means whereby whenithe switch lever is in position for causing the frame to move 'up'wardly the switch lev'ercannot be moved to position for causing the frame to move downwardly without flrst moving the locking lever to itswithdrawn Position.

6. In a hoist of the class the post, an electric motor carried by the frame, a

gear wheel carried by the frame, means for operswitch mechanism associated with the moton'aspring actuated .pawl carried by the frame and described, the combination of an-upright post,ia rack on. the post, a frame capable of up and down movementon normally engaging the rack to prevent downward movement of the frame, a switch lever fulcrumed to the frame and operatively connected with said switch mechanism, a locking lever fulcrumed to *the frame and normally in such position that it will prevent movement 'of the said switch lever to position for causing the motor to lower the frame butwill permit such movement of the switch lever when the locking lever is moved to a withdrawn position, and means associated with said levers for preventing movement of the switch lever from either of its operative positions to theother until after the locking lever has been moved to its withdrawn position. a

7, In a hoist of the class described, the combina tion of an upright post, a rack on the post, a

-frame capable of up and down-move ment on the post, an electric motor carried by the'frame. a gear wheel carried by *theframe, means for operatively connecting the motorwith the gear wheel, switch mechanism associated with the 'motor,'a spring. actuated pawl carried by the motor to lower the frame but will permit such movement of the switch lever when the locking lever is moved to a withdrawn position, means operated by a movement of the locking lever to.

said withdrawn position for moving said; pawl away from said rack, and means associated with said levers for preventing movement of the switch lever from either of its operative positions to the other until after the locking lever has been moved to its withdrawn position.

8. In a hoist of the class described, the combination of an upright post, arack on the post,

the post, an electric motor-carried-by the frame. a gear wheel carried by theframe, means for operativelyconnecting the motor with .the gear wheel, switch mechanism associated with the motor, a spring actuated awl carried by the frame and normally engaging theracli to. prevent nected with said switch mechanism, a locking ,leverfulcrumedto 'the frame and normally in such position that it will prevent movement of the said switch le ver to position for causing the motor to lower the frame but will permit suchnfove'ment of the switch lever when the locking lever is moved to a withdrawn position, and means for connecting the pawl with the locking lever whereby the. pawlmay freely moveinto and out of engagement with the rack teeth when the locking lever is in normal position, and whereby when the locking lever is moved to its withdrawn posi-' tion the pawl will'be moved ,to position but of contact with the rack, 1

9. In a hoist of the class described, the combination of a frame, four upright posts at the I corners of theframe, a rack for each post, a, gear wheel carried by the frame for engagement with the 'raclr'of each post, means for simultane- 'iously rotating the gears for raising and loweringthe frame relative to the posts, said posts being capable. of vertical movement relative'to a'sup'iport upon which they are mounted, and-whereby when the downward movement of the frame is stopped during the continued-rotation of the gears the posts maybe moved upwardly by the action of said gears.

10. In a hoist ofthe class described, the combination of a frame, four upright posts at the corners of the frame, a rack for each post, a gear wheel carried by the frame for engagement with the rack of each post, means for simultaneously rotating the gears for raising and lowering the frame relative to the posts, said racks being capable of up and down movement, and whereby when the downward movement of the frame is stopped during the continued rotation of the'gears in the direction for lowering the frame, the racks may move upwardly.

11. In a hoist of the class described, the combination of a frame, four'upright posts at the corners of the frame, a rack for each post, a gear wheel carried by the frame for engagement with the rack of each post, an electric motor carried by the frame and operatively connected to all of said gear wheels, for driving them simultaneously for raising and lowering the frame relative to the posts, or raising and lowering the posts relative to the frame, an electricswitch for the motor, and

a control device for the electric switch, carried by one of the posts and arranged to cut off the current to the motor and stop further downward movement of the frame when the frame reaches its downward limit of movement or when the post on which the said control device is carried is elevated.

12. In a hoist of the class described, the combination of a frame, four upright posts at the corners of the frame, a rack for each post, a gear wheel carried by the frame for engagement with the rack of each post, means for simultaneously rotating the gears for raising and lowering the frame'relative to the posts, said racks being capable of up and'down movement, and whereby when the downward movement of the frame is stopped during the continued rotation of the gears in the direction for lowering the frame the racks may move upwardly, and means for automatically stopping the rotation of the gears when the frame has reached its upper and its lower limit of movement.

ELMIER B. THOMPSON. 

